This invention relates generally to compression molds and a method of making same and more particularly, to an improved mold apparatus fabricated from a plurality of sheet metal plates of relatively minimal thickness.
Compression molding usually involves the provision of cooperating punch and cavity mold components mounted within suitable structure producing a reciprocating movement between the two opposed components. A conventional mold component comprises a unitary block of massive metal which has been machined to provide the required surface configuration in order to produce the desired molded part. Such construction is necessary in a production operation since it is not uncommon for compression mold components to be subjected to thousands of molding cycles per day, with a lifetime duty often involving hundreds of thousands or even millions of cycles. Thus, the conventional compression mold components must be machined from massive unitary metal blocks so that the mating or cooperating mold surfaces will maintain the precision dimensional relationship therebetween throughout its expected lifetime of use, it being appreciated that each molding cycle usually involves extreme pressure.
The cost of constructing the components of a compression mold assembly comprises a major expense which is usually justified in view of the anticipated production run scheduled for the components. The large manufacturer or a small business man with an order for a large production run of any particular molded part can justify the expense of a machined compression mold assembly. On the other hand, a small producer or anyone desiring to form only a few parts from any one mold assembly, could not normally afford to undergo the expense of having compression mold components machined to particular specifications since the limited production run would not begin to recover the cost of such an expensive apparatus.
In addition to the cost factor discussed hereinabove, the lead time for a molding operator to acquire conventional compression mold components is significant. By the present invention, an improved compression mold apparatus is proposed and which readily lends itself to filling a void encountered by a small producer or any producer who desires only to form a limited number of molded parts according to a single specific mold assembly. Experimental operations will substantially benefit from this invention as it will enable the rapid and economical fabrication of compression mold components particularly adapted for the formation of prototype molded parts. In the past, considerable deliberation has been required on the part of management before agreeing to commit funds for the construction of the more conventional machined compression mold components and often only the large manufacturer could afford such expense when the mold apparatus was not to be utilized in a production-run operation.